Objective: To report a recent fatal case of encephalitis associated with evidence of Murray Valley encephalitis virus infection, only the second fatality from this infection in Western Australia.
Clinical features: An 18-month-old Aboriginal boy was admitted to hospital in northwest Western Australia with proven Haemophilus influenzae type b meningitis.
Intervention and outcome: After an initial good response to antibiotics (amoxycillin and cefotaxime) he relapsed and died with evidence of encephalitis. Analysis of serum showed a high titre of antibody to Murray Valley encephalitis (MVE) virus with the presence of specific IgM. No evidence was found for other infective agents.
Conclusion: It is likely that this child died from MVE which followed his bacterial meningitis. Of the strains of mosquitoes trapped in the area of suspected infection 77.8% were Culex annulirostris, the major vector species for MVE. No MVE virus was isolated from these mosquitoes, but serum from one of the sentinel chickens contained MVE virus antibodies, indicating the presence of the virus in that region.